A: In last week’s blog, we talked about how deep your pond needs to be to overwinter your fish outdoors. As promised, this week we’ll talk about what to do if your pond is less than 18 inches deep or you think your temperatures are too cold outside for your finned friends.

Bring ‘m Inside!
Do you have a pole barn? A garage? A basement? An unused outbuilding? These places make perfect indoor places to overwinter your fish. Koi and goldfish begin their wintertime dormancy at about 45 degrees Fahrenheit, so it’s best to choose a space that hovers at about this temperature or below.

Stock Tank or Holding Tank: This will be your indoor pond area. Because your fish will be dormant they won’t need a huge pond to live in, so you can get away with smaller quarters. Choose a tank that’s sized appropriately for the number and size of your fish. To make the transition easier, use a siphon to fill the holding tank with water from your pond.

Pond Netting: The close quarters might surprise your fish and they could try to make a jump for it, so make sure you cover the tank with The Pond Guy® Premium Pond Netting and secure it with bungee cords or other tie-downs. That will keep them safe and secure.

Aeration System: Just as you aerate your water garden, you’ll need to aerate your holding tank to keep the water oxygenated. An energy-efficient PondAir™ Aeration Kit will work in setups up to 2,000 gallons; a KoiAir™ Aeration System will work in larger setups with more fish.

Wintertime Chores
Caring for your fish in their indoor digs is similar to what you do when they’re outside. Because the living quarters are cramped, check your water parameters with a test kit once a week or so to ensure the water quality is safe. Also, check you water levels and add water as needed, and keep an eye on the equipment to make sure it’s working properly.

Other than that, your fish should be just fine through the winter. Once spring rolls around and water temperatures warm up, they’ll be ready to stretch their fins!

Pond Talk: If you overwinter your fish indoors, what kind of setup do you have?

Q: My pond is 18 inches deep. Can I overwinter my fish in my water garden?

Jessica – Hope Valley, RI

A: Great news! Unless you live in an extremely frigid climate, your pond is at the minimum depth required for overwintering fish in a pond. Though 24 inches or deeper is better, 18 inches should give your finned friends enough room to ride out the cold temperatures—as long as you keep a hole open in the ice.

Freezing winter temperatures will create a solid layer of ice on your pond’s surface. Below the ice sheet, decaying vegetation and organic matter release harmful gases, like ammonia, which can build up and kill your fish. A hole in the ice will allow for gas exchange. The oxygen will enter the pond, the gases will escape, and your fish will stay happy and healthy while they’re hibernating.

To keep that hole open, here’s what you’ll need based on your zone:

Occasional Below-Freezing Temps: For temperature zones that get the occasional below-freezing day or low nighttime temperatures, use an adjustable air stone aerator, like the Airmax® PondAir™ (up to 2,000 gallons) or Airmax® KoiAir™ (up to 16,000 gallons). One of these units will infuse your pond with oxygen while remaining quiet and cost-effective.

Long Stretches of Freezing Temps: For temperature zones that see long stretches of freezing temperatures, we recommend these options, below, based on how many gallons your pond holds. The aerator-deicer combo will give your smaller water garden the one-two punch it needs to vent harmful gases and keep your fish safe, while the more powerful KoiAir will sufficiently aerate larger ponds: